Conventional gates are used either to prevent unauthorised access to a site (security), or for access control purposes.
Security gates prevent vehicular access and are constructed in a variety of formats. Typical examples incorporate sliding, swinging, or vertically raising (or lowering) panels, and are constructed of steel tube, wood, steel mesh, plastic, other materials, or combinations of these materials. The gates may be manually opened, or may utilise one of a number of alternative hydraulic, electrical, electro-hydraulic, or other actuation mechanisms. Automatic control devices may also be provided, to allow for remote (wireless) or security system opening of the gate. As well as preventing unauthorised access, these gates also provide access control.
Another form of access control gate is the boom gate, constructed typically of a long wooden, aluminium or steel beam pivoted about a horizontal axis at one end. Applications include access control into public car parks, and as warning devices at railway level crossings. Boom gates are used more for access control, than security purposes, as it is not very practical to construct them strong enough to prevent deliberate unauthorised access. These gates may also be automatically, manually, or remotely opened and closed.
A number of functional weaknesses may be noted for most conventional gates, particularly automatic gates.
Most automatic gates are quite expensive to purchase and operate, as the gate panels are heavily and expensively constructed, their actuation mechanisms are large and costly, mechanical and electrical or hydraulic services must be installed and connected between the gate and a suitable source, and considerable work is needed to provide the foundations for the necessarily precise gate mechanisms.
Existing gates are also not very space efficient. For example, a swinging gate must have room for the gate panels to swing into, and the panel of a sliding gate requires at least the full opening width again, behind an associated fence. Similarly, poles that are raised telescopically from a hole in the ground require substantial below-ground excavation, and are prone to jamming due to the ingress of sand and water.
Further, many gates are not constructed strong enough to withstand deliberate attempts at unauthorised access, and most automated gates are relatively slow to open (for safety reasons).
Conventional swinging, sliding, or raising gates also tend to be quite slow to open and close, particularly if they are built heavy and strong to withstand deliberate attempts at unauthorised access. The reasons are twofold. Firstly, the inertia of these types of gates is large, requiring high accelerating forces to achieve reasonable speed of operation. This would require large and expensive actuation mechanisms, making the whole approach commercially unattractive. The second, and more important reason, is that heavy gates travelling at high speed (and using high forces) would present a serious hazard to personnel, animals, and equipment such as vehicles. This is because, due to the extremely high inertia levels that would be involved, their overload protection and other safety devices would be rendered ineffective. This is particularly the case if the gates are automatic, and therefore may be operated unintentional, or unexpectedly.
Slow opening times can be particularly annoying to the user, who may need to make regular authorised accesses to a secure site. For example, this may include a home owner entering his own property, or someone wishing to legitimately enter a private parking area. Generally, it is usually not so important for the gate to close quickly.
A further problem with existing gates is their operation when their power source is removed, either through a power failure or illegal means. In many cases, the gate is configured to automatically open in the event of a power failure, for example the gate is no longer held closed, as a spring acts to open the gate. Obviously, security is compromised in such situations.